But unused_results is an allow-by-default lint, so you don't even get a warning. At the very least I think it should be a warn-by-default. I don't see how it's overzealous: I'd much rather know about ignored results. The workaround is to explicitly ignore the result you want to ignore, but that seems like the right thing to do in most such cases rather than overzealous.
@scottmcm says:
Maybe it's just because it's allow by default, so people either don't know about it or don't want to change the rules from the default?